Add aspect-ratio composition band and RAW DNG sidecar capture

src/types/index.ts

@@ -1,5 +1,16 @@
 export type FrameId = 'none' | 'polaroid' | 'classic-white' | 'cinematic' | 'wallframe';
 
+// Viewfinder/composition aspect-ratio selector. Convention is an UPRIGHT
+// (portrait) picture: "4:3" = standing 3:4 photo (w/h = 3/4), "3:2" = standing
+// 2:3 photo (w/h = 2/3). "full" = current fullscreen behaviour (no ratio crop).
+// Wall Frame ignores the ratio (frame + export keep fullscreen as before).
+export type AspectRatio = 'full' | '4:3' | '3:2';
+// w/h of the final upright photo for each non-full choice.
+export const ASPECT_RATIO_W_H: Record<Exclude<AspectRatio, 'full'>, number> = {
+  '4:3': 3 / 4,
+  '3:2': 2 / 3,
+};
+
 // Cinematic seasonal atmosphere grade. Not a fake re-light: it reads the
 // photo's EXISTING exposure — warm tint + soft glow on areas already lit,
 // cool tint in shade, plus a seasonal atmospheric haze/fog veil.